Plasma leptin (mean±SD, 2.8±1.6 vs. 7.6±4.9 ng/mL) and percent body fat (%BF, 16.8±4.2 vs. 26.9±4.9%) were lower (P<0.01) and body surface (BS)-corrected AA higher (P<0.01) in males, whereas plasma cortisol and BS-corrected bioactiveGCs were statistically undistinguishable between the sexes. Both bioactiveGCs and AA correlated positively with %BF and leptin in males (P<0.05), but not in females. After adjusting for AA, NAE was a positive (P=0.011) and leptin a negative (P=0.046) predictor of bioactiveGCs in females (total explained variability R2=0.71). In males only AA explained variation of bioactive-GCs (R2=0.49, P=0.004).

Our findings indicate that  at least in females  variability of potentially bioactive glucocorticoids is not only explained by individual adreno-cortical activity, but may also be affected by circulating leptin and diet-dependent daily acid load.